Field
The present disclosure relates in general to an antenna and, in particular, to a patch antenna.
Background
Circularly-polarized patch antennas are commonplace, with well-understood properties. These antennas are usually single-resonance, limiting the circular polarization bandwidth. Dual-frequency circularly-polarized patch antennas have in the past required dual or multiple pin feeds, complicating the design by requiring additional system components (see U.S. Pat. No. 5,815,119 A). Other designs involve shorting elements (U.S. Pat. No. 4,218,682 A), or, the dual resonances are near together in frequency. These elements either complicate the feed subsystem design or complicate the construction. Additionally, modifying the design of a dual-band circularly polarized antenna can be difficult, or the frequencies of the bands are limited to those that are harmonically related.
What is needed is an integrated circularly-polarized antenna with dual frequency operation which is easily integratable into a system using a coaxial connection without the limitations previously observed.